Selling back college textbooks at the end of term to a mobile buying operation using a hot dog cart, on the George Washington University campus.
Boston Business Journal has a story, "Could Boston be 1st in Fashion Trucks: 7 Startups need Newbury Street Parking," on how the City of Boston is going to permit 7 mobile trucks to sell fashionable clothes. I think that this form of "pop-up" retailing is interesting, but will be difficult to pull off successfully with longevity because apparel in particular is a "specialty" good, and people like to shop different stores before they buy.
But it reflects a couple things. The difficulty of finding a place to sell. The fact that so many of the hours during the week that a store is open are unproductive from a revenue standpoint, since the majority of retail sales transaction volume occurs Friday through Sunday.
The "upscale" container market in Brooklyn, the Dekalb Market (story from Inhabit) is another way to reduce barriers to entry, and to restrict hours of operation so that they more closely match the times when people are more apt to buy.